The field of this invention is generally sliding doors for railroad freight cars and more specifically this invention relates to a replacement wheel assembly for such freight car doors and the method of installing the same.
One form of railroad freight car door which is used quite extensively in this country is a sliding door that is mounted on rollers or wheels which engage a track alongside of the freight car door. Each door is made out of sheet steel formed and welded together and is quite heavy. The normal complement of wheels for each door is two and these wheels or rollers are mounted on the ends of a bar. This bar is connected to a cam and lever arrangement so that a lever may be manually swung by an operator to raise or lower the bar which in turn raises and lowers both of the wheels.
These freight car doors have chambers formed adjacent to their bottom edges and the bar, cam and wheel arrangement is disposed in the chamber connected to the exterior of the door to enable manipulation thereof. There is a peripheral bottom wall which partially defines the chamber, and slots in the bottom wall aligned with the respective wheels of each pair. With the bar raised, the wheels are retracted into the chamber through the slots and the bottom wall rests upon the track. Other guiding means prevent the door from moving laterally away from the side of the freight car but its weight engaging the track or rail frictionally prevents the freight door from sliding.
When it is desired to move the freight door, the operator grasps the lever and swings it one side or the other thereby pushing the bar downwardly carrying the wheels with it. The wheels move through the slots in the bottom wall of the door against the track or rail and this raises the freight car door. The lever has a relatively short throw from its pivotal point to the cam surface and a relatively long arm serving as its handle so the mechanical advantage enables manual raising of the door. The lever is held in place by the operator who then is enabled to slide the door on its track or rail until he releases the lever.
While it is true that the mechanism is protected from the elements and from being bumped or distorted by merchandise containers, fork lifts and the like, nevertheless, the mechanisms have proved to be unsatisfactory because they wear rapidly and because they are relatively complex and subject to breakage.
Replacing or repairing these mechanisms, and the wheels thereof especially, is a difficult and expensive proposition because obtaining access to the chamber within which the mechanism is disposed requires disassembling the door.
The invention solves the problem by an economical and simple replacement wheel assembly that can be installed without removing the freight car door from its mountings and without use of any complicated procedure.
The invention is concerned with the replacement wheel assembly and the method of using the same to replace an inoperative wheel of a freight car door.
The invention is concerned with the construction of the replacement wheel assembly and the method of using the same to repair or refurbish an inoperative sliding freight car door irrespective of whether an original wheel is broken or inoperative or the mechanism itself is inoperative. In the latter case, both original wheels are removed and replaced by two wheel assemblies of the invention.